This invention relates to an apparatus for causing vehicles to travel autonomously, which can be applied to the technical field of civil-engineering machinery where unattended transport vehicles hauling loads of, for example, mining travel along fixed lanes.
At a mining site is generally required a technique for causing an unattended machine to perform the mining operations for the purpose of enhancing safety and reducing mining cost. In case of strip mining wherein minerals near the earth's surface are collected by constructing the spiral lane downward instead of digging mining shafts and tunnels, excavation activity takes place at the deepest point and excavated earth and mined minerals must be hauled out of the mining site. Huge vehicles having an enormous load capacity such as giant dump trucks can be used for the transporting purpose. Since the amount of transported load per unit time directly affects the degree of progress in mining operation, the high-speed transportation of load is required.
In order to haul a great amount of dirt and minerals out of the mining site with high efficiency, plural transport vehicles must reciprocate along fixed transport roads so many times. Consequently, the probability that vehicles traveling the lane toward the mining site may collide with vehicles traveling the lane back from the mining site, will increase. One way of lowering the risk of collision while the vehicles are traveling at high speeds is to make the widths of the transport lanes large. The widening of the transport lanes, however, gives rise to a problem that the mining area is accordingly decreased.
JP-A-2004-157934 and the U.S. Pat. No. 6,941,201 disclose the method for solving this problem. These documents disclose an invention wherein a road is constructed whose width is wide enough for two vehicles to pass by each other safely when they travel the lanes near the road shoulders at reduced speeds, and wherein a vehicle traveling alone without any other vehicle around itself can travel the lane located in the middle of the road, two vehicles approaching toward and supposed to pass by, each other switch to the side lanes near the shoulders of the road with decelerating speeds, and the vehicles after having passed by each other return to the central lane and travel at higher speeds.
The U.S. Pat. No. 6,292,725 discloses an invention wherein two approaching vehicles pass by each other at high speeds on the portion of the road having so sufficient a width that the vehicles can pass by each other safely, and the collision of the two approaching vehicles can be avoided by causing one vehicle to pass by the other while the other vehicle is at rest, where the road becomes narrow.